The invention relates to the field of implants used in human surgery to reconstruct or augment various body parts, in particular breast implants.
In dealing with breast augmentation, four undesirable side effects have plagued researchers and surgeons for over forty years. These side effects are:
1) an unsafe implant. Safety arguably is the most important factor facing the medical implant community and to date there has not been an ideally safe implant eliminating both short and long term toxic local and systemic outcomes such as autoimmune diseases and silicone related inflammations.
2) gel/saline “bleed”. This “bleeding” of fill material causes distasteful feel and an unacceptable cosmetic appearance (such as a deflated saline implant requiring another surgery) and local silicone related inflammations;
3) capsular formation. Scar tissue capsule formation usually forms around the implant frequently causing a rock hard implant with further distasteful feel, dislocation and pain, often times resulting in subsequent surgeries to cure or diminish the complicating factors of such scar tissue formation.
4) loss of sex appeal. The capsular formation referred to above results ultimately in the loss of the desired and hoped for added sex appeal that cosmetic surgery usually promises.
More specifically, unsafe implants and in particular breast implants have caused a wide, seemingly endless array of catastrophic outcomes. The United States Food and Drug Administration (FDA) decreed in early 2004 the continued clinical hold from the market of silicone implants for first time breast implant patients. The FDA called for extensive re-evaluation and further testing of the potential for rupture, thought to cause systemic disorders. Included in this list of clinical problems are silicone mastitis and migration of free silicone into major organ systems such as the liver. This potential continues with every current implant offered.
Numerous complications related to the use of silicone are known and include the use of free silicone injections in the early 1960's, which ultimately resulted in coalescing of the silicone into silicone mastitis (hard lumps throughout the breast tissue) making the diagnosis of invasive cancer of the breast most difficult and resulting in a near impossible mammogram to read. Following these early attempts of free silicone injection came silicone gel encased in a silicone sac. All these silicone implants, although having a so called “sexy feel,” produced gel bleed or outright rupture in a number of cases, resulting locally in hard lumps in the breast as well as systemic migration of the silicone into major organ systems such as the liver. Some studies have shown not only the development of serious systemic side effects such as scleraderma type autoimmune disorders but also the development of various antibodies against the women's own collagen. Further, in some patients, “leaching” of silicone from the wall of an intact implant by select macrophages produced the same undesirable and dangerous systemic side effects without implant rupture.
A number of revisions to the silicone sac were proposed, including single and double lumens. The double lumen implant with silicone residing in the inner sac surrounded by a saline filled outer sac was thought to be the answer to the above problems, and indeed, the double lumen implant offered for the most part a continually soft feel implant long term and without as much capsule formation as opposed to the single lumen. However, over the years it was learned that the internal sac was prone to rupture on occasion, which now meant that the patient and surgeon worried about the integrity of the remaining outer sac, and if it should be replaced (accounting for another expensive operation with its own associated risks), since the previous double lumen implant was now a single lumen sac.
Further investigation into the problems of silicone use led to the development of saline single lumen sacs. This development eliminated for the most part the widespread effects of free silicone in human tissue, but it did not have the safety of the double lumen which afforded some protection from a ruptured implant and consequent spilling the contents of the sac into the tissue. While free saline in the tissue did not result in the same problems as free silicone, the single lumen saline sac at times resulted in a totally deflated implant and the necessity of another operation with its expense and risk. Further, the reported incidence of deflation as reported by Grossman, “The Current Status of Augmentation Mammaplasty,” in Plastic and Reconstructive Surgery 52:1 (1973), reaches as high as 76%. This saline bleed results in “crinkling” of the sac and in some case “sloshing” of the remaining saline in a less then filled implant, and further results in an extremely distasteful feel to the now crippled implant. The result is A decidedly un-sexy implant, exactly the opposite result from what the patient wanted, thereby defeating the purpose of undergoing the cosmetic procedure.
A review of the patent implant literature finds several patents that discuss the problem of capsule formation, specifically U.S. Pat. Nos. 4,955,907, 4,731,081, 5,571,183, 5,207,709, 5,354,338, 4,428,082, and 4,298,998. While these patents propose solutions to capsule formation, all have several common denominators which have the potential of making them unsuitable for resolving this problem in human beings. For example, U.S. Pat. No. 4,298,998 discloses causing a capsule to form at a predetermined, controlled distance from the surface of the implant, thus resulting in the same capsule but at a different location. The end result clinically appears to be a hard capsule for the patient and not resolving the problem.
Similarly, the implant of U.S. Pat. No. 5,207,709 includes a plurality of fin projections extending from the outer surface arrayed in a basket weave-like, herringbone-like, or other suitable pattern to create a sinuous path for collagen formation around the implanted device. It appears that this implant actually creates or invites collagen formation again in another location around the implant, again not resolving the problem. Still other patents relate to the implant being surrounded by a medical grade elastomer or as U.S. Pat. No. 4,944,749 states, a viscous gel coating with the membranes constructed of a suitable material such as medical grade silicone rubber which does not react with human tissue. The outer membrane contains an amount of viscous gel, for example a silicone rubber gel of medical grade silicone. It appears in the end that this patent still has a silicone tissue interface that has accounted for problems.
U.S. Pat. No. 4,610,690 is directed to an implant with a lubricious layer of an acrylamide polymer radiation bonded to at least one wall surface of a silicone shell or bag. Potential long-term effects in human beings of an acrylamide polymer interface are not discussed.
All these aforementioned patents continue to have unnatural chemicals as the interface with human tissue, which is exactly what patients do not want in their body.
U.S. Pat. No. 4,995,882 proposed an organic fill solution to the implant problem. This implant proposed the use of a triglyceride fill substance such as peanut oil or sunflower seed oil as the ideal filler. Although some were implanted in Europe, they were never authorized for implantation in the United States and were subsequently taken off the market worldwide because of various problems.
In U.S. Pat. No. 5,500,017 (incorporated herein by reference), of which the Applicant is a co-inventor, it was proposed to use a sugar syrup, preferably honey, to fill the implant sac. The use of honey is thought to present the following advantages:
1) safety. Since honey is organic, natural and edible, and bio-compatibility studies show low toxicity associated with honey-filled breast implants even with free honey injected into living tissue;
2) honey-filled breast implants, because of the viscosity of honey (at least 15 cp), have the feel of a natural breast which are mimicked by silicone;
3) the United States Department of Agriculture has extensive studies and regulations regarding grades of honey.
Applicant found however, that the use of honey did present some problems. While every other implant had a problem with gel/saline “bleed,” the honey-filled implant had a problem with interstitial body fluid migrating into the sac. This migration is caused by an osmotic gradient whereby the viscosity of the honey inside the sac forces less viscous interstitial fluid into the sac to create an equilibrium. This migration results in an incremental increase in the weight of the implant, which made its ultimate use prohibitive. Also, while honey is safe for most individuals, there are some persons who may be allergic to honey, making a honey-filled sac unsuitable in this sub-population.